Automatic telephone system



April s, 192s. 1,519,831

W. T. POWELL AUTOIATIG TBLEFHONE SYSTEM ono aEcoN'DARY um: swrrcH.

FIGLI PR'MARY LHE wiTCH *fj l o n a BY ATTORNEY April 6 1926.

F l G PRIMARY SELECTOR.

SECONDARY SELECTOR.

W. T. POWELL AUTOIA'IIQ TELEPHONE SYSTEM Filed Oct, 23, 1922v 4 Sheets-Sheet 2 y mvENToR WINF'RED T. POWELL BY M ATTORNEY 1,579,837 W. T. POWELL AUTOMATIC TELEPHONE SYS'vl'EI Filed Oct. 23 1922' 4 Sheets-Shed 3 LO-{lh ATT RNEY NVENTOR WINFRED T. POWELL.

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April s, 1926.

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OFFICE a INVENTOR WINFRED T POWELL.,

ATTRN'EY I Patented liipr.` 6, 1925.

WINEEED T. POWELL,

0E ROCHESTER, NEW YORK, Assieiionj fro THE srnoicnnne- CARLSON TELEPHONE MANUFACTURING COMPANY, OF ROCHESTER, NEW YORK, 'A

CORPORATION OF NEW YORK.

,AUTOMATIC TELEPHONE SYSTEM.

Application led October 23, 1922. Serial No. 596,280.

To all whom it may cono-cwi:

Be it known that I, 1vViNrnnD T. POWELL, a citizen ot the United States, residing at Rochester, in the county of Monroe and State ot New York, have invented certain new and useful improvements in Automatic Telephone Systems, of which the following a full, clear, concise and exact description.

This vinvention relates to telephone systems, and more particularly to telephone systems employing automatic switches in completing some portion ot a telephone coni'iection.

ln manual tclephonesystenis, it becomes desirable, either trom commercial or operating reasons to replace certain portions of the manual equipment by automatic switches while still retaining certain ot the offices of the system on a manual basis of operation. l-ven those ottices in which automatic switchare installed, 'it is sonitimes desirable to retain the manual line equipment such as the line and cut-ott relays, to cooperatewith the relays ot' the autoinatie'switches. 1

@ne ot the features ot the present invention is the novel arrangement by whichautomatic ottices Vand manual otlices of a telephone exchange are arranged to cooperate.

Another feature ot the invention is the novel arrangement by which the numerically directed switches et the` system may be selectivelyv operated. l Y Other features of the invention will appear iti-om the detailed description and appended claims.

rlhe drawings with Figs. 1, 2, 3, and 4 arranged in the order named diagrammatically represent a portion of a telephone system including the above mentioned features. At the lett of the dotted line in Fig. 1 there are represented substations and lines of two subscribers which lines terminate` `in the brushes oft a non-numerical lineswitch. It will be seen that the line and cut-ott relays as well as the calling yjacks of the lines of` sub-station A and C is equipment which has been retained trom the time when these lines i At the'iight V ot thc dotted line ot Fig. 1 there is reprei were used: in Va manual ottico.

sented an odd secondary lineswitch and an eren Fig. there'is represented. the operating cir cuits cte priinaiy numerical selector switch,

secondary line switch. VAt the lett ot'" while at the right otk the dotted line of Fig. 2 there is shown a secondary selector switch which is entirely non-numerical in operation. Above the dot-ted line of Fig. 3 there is diagrammatically shown a so-called repeater arrangement for repeating impulses from a dial sender, such as that at substation A to adistant automatic oiiice such asshown in Fig. 4.' In the lower left hand corner of Fig. 3

there'is shown a so-called repeater arrangement, which cooperates in extending a telephone connection :trom an automatic telephone line such as that leadingV from substation A to a telephone line terminating at a distant manual. otlice, such as that represented in the lower right hand corner of Fig. 3. Fig. 4 diagrammatically discloses the operating circuits of a so-called connector switch as well as one ot .the lines and its sub-station B which terminates in this switch.

The line switches of this disclosuieas well `as the primary and secondary selector switches may bey ot the type substantially similar to that disclosed in the patent to Clement No. 1,107,153, granted August 11, 1914. The connector switch may be of the type somewhat similar to that disclosed in the patent to Keith, Erickson & Erickson No. 815,176, granted March 13, 1906. The present connector switch differs from that diselosed'in the mentioned patent by beingarianged to operate yin a so-called two-wire system, also the terminals of theconnector bank instead ot being arranged in ten levels with ten sets ot contacts in each level are modified by being arranged in twenty levels with tive sets of contacts in each level. Also the switch, instead of being provided with a single set of three brushes, is provided with tour sets of brushes with three brushes in each set. i

It is believed that the invention will best be understood by describing the method ot establishing al telephone connection from a substation such as A to a wanted subscriber at a distant automatic oiice and by describing subsequently a connection to a subscriber at a distant manual otice.

lVhen the subscriber at A removes his completed for the line relay 5 grounded battery, winding oit thiip armature andback contact ottliy -ielay 6, over the lower side ot the- 7,

- from receiver Jfrom its switch hook a ycircuit is tance, inner armature larmature ot switching relay i) i t; nder line and substation circuits in series, over the upper side ot' the calling line, inner back contact and armature of relay 6 to ground. The line relay is energized in this circuit and coi'nplete's an operating circuit for the reiay 7 from grounded battery, Winding of this relay, contact and armature of relay 5, to ground. rlhe relay 7 on operation closes an actuating` circuit for the motor magnet 8 tracea le from grounded battery, resisand liront Contact of relay i", Winding, back contact and armature of motor magnet S, outer front Contact and armature of relay 7, lower back Contact and to ground. the control o1c this circuit the motor magnet of 'the primary line switchudvances "l i shes l0, ll, l2, 13, ll, l5, ai l 16 until r 'of idle primary ti'unlsis located, 'lL Vch condition is indicated by the presence ot ground potential on a test terminal such as l? individual to such pair of trunks. X

.Then such an idle terminal located, circuit is closed from ere-uno at the arma- Yure and back; cont-act oi relay 18, test terminal 17, test brush 13, low'resisuance Winding` of relay 9, conductor l5), inner front contactand armature of relay 7, resistance, to grounded battery. lt will be noted that the motor magnet 8 is'short circuited by the completion ot this circuit u'hile the r l y 9 is operated to extend the calling` line through its upper iatures and front conanfl the brushes l0 and ll the prin? "y line switch to the selected primary trunk. The sionv releasingv relay 2O ot the odd secondary line switch thus has a circuit closed from grounded battery, Winding of this relay armut .re and l Contact of relay over the lower side of the selected rush ll, over the loner side of the callin;- line and substation circuits in series, ver the upper side oi" the calling` line to round at e inner back Contact and armature of relay Relay 2O when thus energized completes un operating` circuit for th mot it il?) et' the odd secondary line s "facealle from `grounded battery, r. "ance, innermost armature `and frontcont:V rt ot' relay 520, Winding', haelt contact and armature of niet-or 1'1iagnet`25 ontei' most front contact and armature ot relay 20, id armatureV of relay er *Lilie control et' this advances the the odd scc- 7 n i wi N lonerL nach con j line switclrru'itil the test te' an idle secondary trunk is loe condition is indicated by il ground potential thereon.

liet it he assumed thatthe ondury trunk tested that Figs. l and 2. Under this tirst` idle appear-nig" in assumption a circuit is closed Jtroni ground at the arma?, ture and baclt contact of relay 30, outer back contact and armature of relay 3l, conductor 142, test terminal Q9, test brush 2S, low resistance winding of relay 2e, inner front lcontact and the armature of relay to grounded battery. This short circuits the ino-tor magnet to stop the brushes Qato 28 inclusive of the odd secondary line switch in enea-gement With the terminals of the idle runlt. This circuit also elilects the energia ation of the switching relayl, which relay at its upper armatures and front contacts extends the calling lineto'the brushes 2.3 and 2S 'of the secondary line switch and through the upper armatures and back conta'cts of relay 32 Fig. f2 to grounded battery andground respectively through the vrindingsot' impulse relay Relay thereupon operates and closes a circuit from ground at its inner armature and front contact for actuating slow7 releasing relay 3l, and this last mentioned relay at outer armature and front contactcloses a holding circuit from grounded battery, resistance, conductor 142, test terminal 7.9, test brush 2S, high-resistance Winding, front contact and armature of relay 2l to ground. rille seizure of the odd. secondary trun i u'ell as 'the energizing ot the switching` relay completes an operating circuit for the relay 2l from ground, Winding of this relay, inner upper armature and front Contact of relay Q4, brush 27, conductor 3%, resistance to grounded battery. At this time the cut-eti relay 6 is also energized in multiple with this last described circuitithrough the inner upper armature and front contact of relay 9 and primary line switch brush lf2.

Let it be assumed that the Wanted line, designated #102 terminates at a distant automatic' otiice, under which assumption the calling subscriber operates his dial sender to transmit, impulses by which the primary selector is advanced to select an outgoing `trunk over which the Wanted automatic line may be reached. lVhen the inipulse relay 33 is thus energized on the seizure ot' its trunk circuit, the motor magnet 35 of the primary selector is operated from grounded battery, Winding, armature and back contact of this magnet, brush 36 ot' the primary selector in its rst position, back Contact and continuityspring of relay 30, primary selector brush 37, outer front con tact and armature of impulse relay 33 to ground. The motor magnet 35` on energiza tion interrupts its own circuit and advances the brushes 36, 37, 38, 39, 40, and el of the primary selector one step. The primary selector is no'W in readiness to receive the first series of directive impulses from the dial sender at sub-station A. In response to each of these dial interruptions the impulse relay retracts and attractsits armatures. On the rstretraction ofv its armature a` cirand back contact of impulse relay 33, s'e` lector brush 37 in its second position, continuity spring and back contact of changeover relay 30', selector brush `36, back contact, armature and winding lot' motor magnet 35 to grounded battery. The motor mag net is thus operated to advance the brushes ott the primary selector into their third position. The change-over relay 30 energizes in multiple with the last-described circuit and on the attraction of its armatures closes a locking circuit orhitselt throughits armature and continuity spring, selector brush 37, back contact and armature of relay 33 to ground. lVith the selector in its third positioma circuit is closed 'from ground, outer armature andy front Contact of impulse relay 33, brush 37, continuity spring and armature of relay 30, back contact, armature and winding of motor magnet 35 to grounded battery. .The motor magnet 35 is thus again energized and advances the priinaryselector vbrushes into their fourth position where it is inreadiness to be operated in response to the next interruption lot this series. It will be noted that in response to each dial interruption the primary selector advances its brushes two steps;

Let it be assumed that the primary selector brushes 38, 39 and 40 have been advanced to the terminals of conductors 42, 43, and 44 of a trunl; leadingfto the brushes 45 46, and 47V of the secondary selector of Fig. 2. I

Atthe close or the first series of interi-up tions, impulse relay 33 holds its armatures attracted for a long enough period to permit the change-over relay 30 to deenergize, whereupon the relay 51 is actuated in a circuit closed from ground at the armature and bacl contact of relay 30, inner, lower armature and back contact of relay 32, winding ot relay 5l, primary selector brush 36, back contact, armature and winding of the motor magnet 35 to grounded battery. This motor magnet is marginal and will not operate in series with relay 51, but this last named relay is energized to complete a circuit from grounded battery, resistance, front contact and armature of relay 5l, lowermost back contact and armature oi relay 32, conductor 53, primary selector brush 41, windingarmature, and bac-lr contact ot the motor magnet 52 to ground. Under the control ot this circuit the motor magnet v52 of ythe secondar f selector advances its brushes 45 to 50 inclusive to locate an idle trunk in the group selected by the. primary selector. The motor magnet 52 continues to operate until the test brush 47 encounters an idle test terminal such as 54 which is characterized by the presence of ground potential to indicate'its idle condition.

Let it be vassumed that 'the first idle trunk located is that shownin the upper right hardA corner @t Fis 2 ,and the lerrer Por tionof Fig. 3. I lhen this trunk is tested, a circuit is closed 'from ground, back con tact and armature 106 of relay 56, conductor 57, test terminal 54, test brush 47, conductor 44, test brush 40, low resistance winding of relay 32V, front contacts and armature olf relay 5l, resistance to grounded battery.

Thiscircuit is eiiective `to short circuit the motor magnet 52, to stop theoperation pt the secondary selector, and it is also effective to actuate the relay 32 whereupon the calling line is extended through the primary selector brushes 38 and 39 and the secondary selector brushes 45 and 46 to the conductors 53 and 59. Conductor 58 is then extendel through the inner continuity spring and back con i tact of relay 60conductor 62, lower winding of the impulse relay 63 to ground. Conductor 59 is extended through the upper continuity spring and back contact of relay 60, conductor 64, upper winding ot the impulse relay 63 to grounded battery. The impulse relay is thus energized to attract its armatures and at its inner armature and front Contact extends a circuit rom'ground, through the winding of slow releasing relay 55 to grounded battery. The relay 56 is thus operated and closes a holding circuit tor relay 32 from grounded battery, resistance, front contact and armature A106, conductor 57, testv terminal V54, test brush 47, conductor 44, primary selector test brush 40, high resistance winding, iront contact and armature of the switching rela-y 32, bach Contact andv armature of change-over relay 30 to ground. j

vThe subscriber at A thereupon transmits a second series ot 4dia-l interruptions corresponding to the second digit oic the wanted number." The repeater circuit shown in the upper portion of Fig. 3 located inthe first oliice, operates to repeat'this series ot interruptions to the numerical switches located at a second oliice. For purposes of this description, a single numerical switch which Vis a connector, has been shown, but it will be understood that one or more of the so-called selectorsy of the well-known type may bel interposed between the repeater randthe connector switch oi Fig. 4. lt Vwill and back contact, lowermost front contact and armature of relay 56,` winding oi relay 65- to grounded battery,.which causes the relay 65 to attractits armatures. `Wit-h the relay 65 energized and when impulse relav 63. @were .itsgarlaeture .is responses;

llO

each inpulse, the Aimpulse relay '66 of F ig. l is energized in a circuit ktraceable from grounded battery, right hand Winding ot' relay o6, outer bach contact and continuity spring of relay '67, 'conductor 68, armature and iront contact of relay "56, lett hand arn'iature and front Contact ot' relay 6 5, conductors '69 and 70,-upperniost armature and trent1 contact ot relay 63, conductor 7l, innermost continuity spring and back contact ot relay 67, lett hand Winding of relay 66 to ground. Gn the iirst energization of relay 66, sionv releasing relay 7 2 is operated in a circuit closed at the lei't 'hand front contact and armature or' the relay 66.

En response 'to the first interruption 01": the tens series, relay 66 retracts its armatures, whereugon a circuit is completed from ground at the armature `and, front Contact or' relay 72, right hand bachv 'contactand armature oft relay 66, Winding of relay 7l, side sritch Wiper 75 to grounded battery. The relay 7 is thus actuated and effects the operation ot slow releasing relays 76, and relay in turn operates the escape. .et 77. it the lett hand a nature and haci; contact ot relay 66, aci 'cuit is closed t'i om und through the left hand armature and front contact ol relay 7 2, lett haii-d a'rinature and baci; contact ot relay 79, winding ot relay 78, left hand Winding of iziarginal relay 79 to grounded battery. The relay 7S is operated in this circuit hut marginal relay 79 is not operated at this time. jrs soon as relay 7S attracts its armatures it completes an energizing circuit tor the primary motor magnet SO from grounded battery, Winding of this magnet, side switch wiper 8l, in its first position, middle armature and front contact ot relay 7 8, front contact and armature of relay 76 to ground. A

The Aen'ergization of relay 78 also closes a second circuit from lgrounded battery, lett hand Winding of relay 79, Winding of relay 7 8, right hand Winding ot relayy 79, innerand front contact ot relay most armature 7 S, front contact and armature of relay 76 to ground. The right hand Winding of relay '79 is short circuited by ground at the Vlett hand armature and back Contact or" relay 6C, until this relay is energized. At

Athe close of this line interruption when impulse relay 66 removes this short circuit, relay 78 is held operated and the relay 79 is operated in the circuit last described. It this .series of interruptions consists of only one interruption, the impulse relay 66 is now held operated for a relatiyely long yal to effect the deenergization ot relays 7l and 76. In the interval, however., between the defenergization of relays 74 and 76 the relay 65 is operated from grounded battery, its lWinding, vconductor 130, `side switch Wiaer 143, out-erinostA armature Vand 'front 'contact l'of "relay 78,*b`ael: contact and armature of relay 711- to ground. Relay 85 on operation closes 'a locking circuit *for itselt 'through its innermost iront contact and armature to ground at the oit-normal contacts 97. The release of relay 76 causes the escape magnet 77 to move the sideswitch Wiper-s into their second position, whereupon the units series of dial interruptions is transmitted to operate the secondary motor magnet 181.

it', lrowe'r'er, the tens series ot interruptions contains two interruptions, at the close ot the iirst interruption of the series, the relays 78 and '79 are both energized. In response to the second interruption of this series a circuit is closet from ground at the left hand armature and back Contact oi relay 66, armature and front contact ot reyay 72, lett hand armature, front contact and Winding o1"l relay 79 to grounded battery. Therelay 79 is held operated in this circa but the relay 78 is short circuited and rel-eases its armatures. It will 'be noted, hott-cre?, that the operating circuit 'ot the prima y motor magnet S is at this time closed throng-'gh the ri g'l-it hand armature and front contact ol relay 79. At the vclose 'of the second interruption of this series, the impulse relay 66 is again operated, and opens the locking circuit just described for 'the relay 79. It 'these' are the only two interruptions in the series, relays 7e and 76 deenergize as a result of the repeated operation oli' relay 66 in the manner already described. ln this instance, howerer, no operating circuit is completed for the relay 85, due to the fact that the outermost armature and l"front contact of the relay 78 is opened.

From the foregoing explanation, it will be understood 'that in response to one interruption the primary motor magnet advances the connector switch brushfone step. It also operates the switching relay S to extend the conductors 7l and 68 of the trunlr to a particular set of connector switch brushes. Likewise in the case of a series of two interruptions, the primary motor magnet 8Ol is operated only `once but at this time the switching relay is not actuated so that a diil'erent set of connector switch brushes is ette'ctive. F rom this it will be understood that the 'connector switch is operated one step tor veach odd interruption. or 'for each pair of 'odd and even interruptions. In the case of lthe odd interruptions, however, a relay such i1-S85 distinguishes between odd and even interruptions lto render effective one or 'another set ot connector brushes. ln the present instance it has been assumed that the Wanted number is 102, therefore the tens series of interruptions are ten in number as arresult of which the primary motorinagnet 80 is operated in the manner already desc" ibedto elevate the connector Yswitch brush rive' vasen stets. nl response to the eine series ot interruptions the impulse relay 66 is energized and deenergized twice with the result that the secondary motor magnet 131 rotates the connector switch brushes one step in their secondary movement. stance the relay 132 is iio't operated due to the-tact that the units series' et interruptions is even in number.

At the close of this ilast series ot interruptions the change-over relay 76 deenergizes at which time the test of the called line is made, which test is etiected in -a circuit completed from ffrounded battery, winding ot the escape magnet 77, 'continuity spring and back contact ot' relay76,' winding or test relay 82, its continuity spring and back contact, side switch wiper 83 in itssecond position, armature Se and back `contact of relay 85, uppermost armature and back contact ot relay 132, test brush 86, test terminal 8T. It the wanted line is idle, its test terminalis characterized by full battery potential applied through the resistance 88, which causes the escape magnet 77 to deenergize to advance the side switch wipers into their third position. rllie called party is now signalled by ringing current applied trom the ringing generator through the inner bach` contact and armature ot trip relay 89, side switch wiper 90 in its third position', armature 91 and back contact, back contactv and .armature 92, connector brush 93, over the lower side ot the wanted line and through the bell at the wanted sub-station, over the upper side of the wanted line, connector brush 9i, armature 95 and back contact` back contact and armature 96 otf relay 85, larmature and back contact of trip relay 8,9, upper winding oit relay 89y conductor 95', side switch wiper to grounded battery. Signalling current is applied Vover this circuit until the subscriber at substation B responds by removing his receiver troni its switch hook, at which time the trip relay 89 is energized to complete a locking circuit for itseli through its lower winding, front contact and armature, off normal conta-cts 97 to ground. The trip relay onenergization also closes a break-point in the talking circuit.

When the called party answers, talking battery is supplied through the winding of relay 67, causing this relay to energize with the result that the current is reversed in conductors 68 and 7l to cause the operation of the polarized relay 98 of Fig. 3. Itwill be remembered that a circuit is closed through the lower winding of polarized relay 98, as soon as relay 56 is operated and when the current is reversed in conductors 4 71 and 68, the upper winding of relay 9S isenergized in such a manner as to cooperate with the lower winding as a result ot which the armatures ot this relay are attracted. The. energizing circuit of the upper windingv of relay ln this in- Y lof relay 31 to ground.

vsecondary line switch is not in use.

Vprimary and secondary 98 is traceable `from grounded battery, right hand winding ot relay 66, inner armature and continuity spring or" relay 67, conductor 71, uppermost front Contact and arma-ture of relay 63, conductors() and 69, right hand winding of relay 997 conductor 100, lowerniost continuity spring and back contactv ot' relay 60, upper winding of relay 98, conductor101, back contact and armature of relay 65., upper trent contact of relay 56,`conductor 68, outer spring and armature ot relay 6'?, left hand winding of relay 66 to ground.r` lith the relay 98 operated, the relay 60 is actuated in ak circuit closed Lfrom continuity 63 through which talking battery is supplied to the calling party, deeiicrgizes and shortly afterwards the slow releasing relay 56 retraits its armatures to open the circuit including conductors 68 and Z 1 leading'to the impulse relay 66, causing-'this relayto` cle/energize. lt will be `remembered that the holding circuit the primary selector including conductor 5r? is controlledfat n the `armature 16de-nd *front contact olirelay 56, so that when this relay deenergizcs the switching relay' 32 retracts its armatures andat its lowerinost armature and trent. contact opens the holding circuit of relay 31. rlhjis causes the releasecircuit ot the primary selector switch to be coinpleted 'from grounded battery, winding, armature and back contact oi motor magnet 35, brush 36 in any of its oil-normal posi.- tions, right hand back contact and armature Under the control of this circuit the primary selector is inoved into its normal, position The release of relay 31V als) opens the holding circuit includi ing conductor 142,'wliich permits the switching relay 2-1 of Fig. 1 to release and at its lower armature and iront contact opens the circuit for relay18, providing that the even rlfhe deenergizntion of relay 18 opcns'the holding circuit. for the vswitching relay 9, which has been completed through line switch brush 13. Also the deeiiergization c ot relay 241- opens the circuit which has been maintaining the relays 21 and 6 operated. Since the line switches are of the type that remain in engagement with and armature j grounded battery,

the trunk last used their circuitsv are now ijn normal condition and in readiness to extend another connection.

It will be remembered that the termination ot' 'the call by the calling. subscriber eil'ected the deenergization oit relay GQ of F ig. 1,'and thisin turn causes the deenergizati'on of the slow releasingY relay 72 where'- upon a releasing circuit is closed from grounded battery, winding ot the release magnet 108, oit-normal contacts 109, left handbacl contacts and armatures of relays 72 and 66t to ground. rlfhe release magnet is thus energized and releases thev connector and its associated side switch into their normal position.v

lt should be mentioned at this point, that if the subscriber at substation Cj originates a call instead of the subscriber at A, the primary line switch` ot Fig. 1 operates in the manner already described, but the calling line extending from subfstation C is instead extended through the brushes 14, 15 and 16 to the even secondary line switch shown in the lower right hand corner of Fig. 1'. 1t will also be understood that the subscribers at sub-station A and` C may simultaneously initiate calls.` In this case the primary line switch seizes an idle pair of trunks leading to an odd secondary line switch and to an even secondary line switch. The line switches operate independently to seize primary selector switches which may be operated in the manner already described.

Let it be assumed that the subscriber at A desires toV converse with` a called subscriber, whose line (not shown) terminates at a dista-nt oce,` such as that represented in the lower right hand corner of Fig. 3. Under this assumption when the calling subscriber as substation A removes his receiver from its switch hook, his primary line switch operates in the manner already described to seize an idle secondary line switch which may be the one shown in 1 and this switch in turn operates to seize an idle prijmary selector switch as shown in Fig.` 2. The calling subscriber thereupon operates his dial sender to transmit a series of impulses Correspondingl to the designation ot the wanted otliee through which the called subscriber may be reached. Let it be assumed that this designation is 2 so that the calling subscriber sends two impulses, in response to whichv theV primary selector switch advances its brushes 38, di) and 10 into engagement with the conductors 109', 110 and 111 ot aV trunk through which the called party may be reached. Thereafter the secondary selector ot' Fig. 2 operates to seize an idle trunk leading to the wanted otlice. It is assumed that `this selector seizes the trunk whose conductors are designated 112, llland 114; leading to Fig` The condition of this idle trunk is indicated by Contactk effects. the operation ci relay 11T,

which in turn applies the source ot' holding battery tothe conductor 114 to maintain the connection. n Also wit-h the relay 117 energized, a. trunk signal at the distant manual otlice'is, lighted inthe following manner. The operationfot relay 117 closes a circuit traceable from grounded' battery, winding ol relay 119, armature and back Contact olirclay 120, outermost front Contact and armature of relay 117, conductor 12-1` ot the selected trunk to the distant oilice, lower side of the repeating call, lett hand winding ot the relay 1-22, upper left hand winding ot' the reir peatingcoi'l, conductor ot the selected t'runlr, winding of relay 116 to ground. The energization of relay 116 removes ground from the conductor 11i to prevent seizure of this trunk when the called portion ci" the connection is maintained, even aiter the calling subscriber releases. Also relay 119 is energized in this circuit and at its ariua` ture and: front contact completes an operating circuit tor the relay 12'. r'his last named relay reverses the connection betr-:een conductors 112 and 113 and relay 11S. rlhe relay 122 is energized in the circuit described` and' lights the trunk lainp 125 in a circuit traceable from battery, lanipo125, resistance, front contact and armature of relay 122, lower armature and bacl contact ot relay 126, resistance to ground.

The operator at the distant otlice on noting that the lamp 125 is lighted, depresses the listening key L, K. to connect her head set to the extended connectionv and inquires the designation of the wanted subscriber. Thereafter the operator connects the tip of the plug of the selected cordlcircuit to the sleeve ot' the jack J, leading to the wanted substation, and the absence ot' a distinctive click in the operatorie` head set at this time indicates to her that the wanted line is idle, whereupon she inserts the plug l) into the jack This operation completes an energizing circuit for `the sleeve relay 126 closed from grounded battery, through the 'lamp 125, winding ot this relay, through the sleeve contacts of the plug and jack and resistance to ground. rlie energirfation ot rclay 126 closes a substitute circuit tor itsel't troni grouiidml battery, its` lower front contact and armature, armature and front contact of relay 122, through the resistance and winding otrelay 126, sleeve contacts of plug and jack, through the resistance to ground.

rseized again.

ln this way the signal 125 is extinguished. The operator now depresses the ringing key R. K. to close a signaling' circuit from ground through ringing generator 128, lett hand winding oil the trip relay 129, contacts o1 the inging key, over the lower side or' the cord circuit, 'through the lring contacts of the plug and jack over the lower side of the called line and its substation (not shown), over the upper side of the called line, tip cont cts ot' the jack and plug, armature and iront contact ol relay 126 through the ringing` key contacts to ground.

It should be stated that although any well known ringing arrangement may be used, the present disclosure makes use ot avringing key lt. K. which is of that design which is locked in its depressed position by arelay such as 127 deeneigization of said relay. called party responds the trip relay operated and thereupon opens the holding circuit ot the relay 127, which releases the ringing key to close break points in the talking conductorsV and to disconnect the ringing generator from the called line.

Talking battery for the calling party is supplied through the windings ot relay 118, while talking battery is supplied to the called party through the right hand windings or' the repeating coil.

At the termination of a conversation when the calling party replaces his receiver on its switch hook, relay 118 deenergizes to effect the release of the slow releasing relay 117', and this last named relay at its louter armature and 'front contact opens the circuit which has been maintaining the-relay 122 operated. The release of relay 122 removes When the 1 O9 is the shunt which has existed' during the con-V versation about the supervisory signal 125, whereupon this signal is'liglited to inform the operator at the distant oiiice to dis-establish the connection by removing the plug P from the jack J. rlhe deenergization ot re lay 117 opens the holding conductor 114 to permit the deenergization of the holding relay 32 in the upper left hand corner of Fig. 2. This relay by deenergizing effects the release ot the automatic switches of the connection in the manner already described.

Let it be assumed that after the calling party has released and the automatic switches ot the connection are in their normal position that the operator at the dis.

tant manual oilice fails to remove the plug l) it'rom the )ack J. Under this condition it isnecessary to prevent the trunk whose conductors are designated 112, 113, and 114 and which lead to the plug P, from being rlfhe seizure of this operators circuit is prevented by gization of the relay 11G, which removes the idle ground condition from test conductor 114. The relay 116 is maintained operated until it is released by theV the continued ener-` in a circuit now traceable from ground, winding ot relay 116, conductor 122-5, upper winding Yotthe repeating coil, back contact and armature ot relay 122, lower armature and front contact or" relay 126 to grounded battery. As soon as the operatorrenioves herplug P from the jack J, this circuit is interrupted. at the lower armature and Jfront contact ot the sleeve relay 126.

lt' should be pointed out that when the ysubscriber at A is called, a plug of a manual cordcircuit (not shown) is inserted into the calling jack ot this line, shown in the upper left hand corner of Fig. 1. rilhis operation is eilective to energize the cut-oil relay 6 in the well known manner which disconnects tlie line relay 'l'roin the called line and thereby prevents the operation ot the primary line switch, when the subscriber at A answers by removing his receiver troni its switch hook.

Attention should also be directed to the fact that as soon as the calling line from substation A has been connected to t-lie repeater, in the lower left hand corner ol' Fig. 3, means are provided to prevent unnecessary flashing of signal lamp 125. lt at this time the subscriber at A operates his dial sender, the impulse relay 118 operates in the manner already described, so that relays 117 and 120 are actuated.v lt will be recalled that the relay117 at its outer armature controls a circuit including conductor 121 and while this series ot impulses is beingtransinitted Lby relay 118, the relay 120 holds the circuit of relay 122 open, thus prew venting the lamp 125 from being flashed.

that is claimed is i l 1. ln an automatic telephone system, an incoming circuit, a plurality ot outgoing circuits, an automatic switch ttor interconnecting` said incoming circuit withl any of said outgoing circuits, a device forgenerating impulses vinr said incoming circuit,v means responsive' to each group ot impulses for advancing said automatic switch one unit of space, and other means controlled by the number of impulses in a group for governing the interconnection effected by said auto-k matic switch. i.

n 2. In an automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch operable through primary and secondary movements rto interconnect said incoming circuit with any of said outgoing circuits, a device for generating impulses in said incoming circuit, mechanism responsive to grouper impulses for advancing said automatic switch one unit of space in either of its primary and secondary movements, and other means controlled by the number `of impulses in' centraiii of said groups for governing the interconnection effected by said kautomatic switch.

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3. l'n an automatic telephone system, an incoming` circuit, a plurality ot outgoing circuits, an automatic switch for interconnecting` said incoming` circuit with any 0i: said outgoing circuits, said automatic switch having sets or brushes, a device for transmittinT impulses over said incoming',` circuit, means responsive to each group or impulses :tor at yancing' said automatic switch one unit oi-l space, and other means governed b f the number of impulses in a group for dctermining which set oil brushes et' said automatick switch is to be elifective in interconnecting said incomingl circuit and a `wanted outgoing circuit.

i. in an automatic telephone system, an incoming` circuit, a plurality ol outgoingcircuits, an auton'iatic switch for interconnecting' said incoming circuit with any of said outgoing circuits, said automatic switch being provided with four sets oi brushes, means including a pair of relays by which the sets ot brushes of said switch are rariably connected to said incoming` circuit, a device for transmittingl impulses over said incoiu ing circuit, mechanism responsive to cach group or impulses lor advancing said automatic switch one unit et space, and other means controlled by a number oi impulses in certain of said groups for variably operating said pair of relays.

5. In an automatic telephone systeni, an 'ncon'iing circuit, a plurality oi outgoing circuits, an automatic switchv Jfor interconnecting said incoming circuit with any of said outgoingcircuits, an impulse relay connected to said incoming` circuit arranged to respond to impulses transmitted over said incoming circuit from a distant point, a motor magnet for advancing said automatic switch, a pair of relays, a circuit for said motor magnet independently completed at each of said relays, means responsive to one operation of said impulse relay for actuating one of said relays, means responsive to a second opera-tion ot' 'rid in'ipulse relay tor actuating` the other of said relays, and means controlled by said pair o'j relays for variably governing the interconnection etlected by said automatic switch.

G. In an automatic telephone system, an incoming circuit, an automatic switch for interconnecting said incon'iingv circuit with any of said outgoing circuits, said automatic switch being` provided with a plurality ot sets oi brushes, a `group of relays for Variably connecting said sets oi brushes to said incoming' circuit, a motor magnet 'for directively advancing said automatic switch, an impulse relay connected to said incoming circuit arranged to be controlled by impulses transmitted thereorer, a. pair or' relays a circuit for said motor magnet completed ou theV operation oit either of said relays, means responsive to a single operation et sai d impulse relay 'for actuating one of said relays Without actuating the ther of said pair of relays, means responsiife to the second operation oi said impulse relay for act auating the second relay o't said pair While retaining` the lire-t mentioned relay of said pair operated, other means responsive to a third operation oi said impulse relay for eiifecting the dcenergization ot the iirst relay and retainingthe second relay oi said pair operated, means responsive to the fourth operation of said impulse relay for deenen gizing` the second Yrelay of said pair, and means controlled by the if'ariable operation .of said pair or' relays for controlling said group of relays to extend said incoming cir- Liit to one of said sets ot brushes and thence to one of said outgoing lines.

ln itness- Wnereo'li, l hereunto subscribe my name this 20th day of October A. D. 1922.

VVINFRED T. POVELL. 

